Move order preservation under a feature gate

18 files changed, 251 insertions, 180 deletions

diff --git a/tests/async_builder.rs b/tests/async_builder.rs
index a614d42..bf923d6 100644
--- a/tests/async_builder.rs
+++ b/tests/async_builder.rs
@@ -1,6 +1,7 @@
+#![cfg(feature = "preserve_order")]
+
 use async_trait::async_trait;
 use config::*;
-use linked_hash_map::LinkedHashMap;
 use std::{env, fs, path, str::FromStr};
 use tokio::{fs::File, io::AsyncReadExt};
 
@@ -19,7 +20,7 @@ impl AsyncFile {
 
 #[async_trait]
 impl AsyncSource for AsyncFile {
-    async fn collect(&self) -> Result<LinkedHashMap<String, Value>, ConfigError> {
+    async fn collect(&self) -> Result<MapImpl<String, Value>, ConfigError> {
         let mut path = env::current_dir().unwrap();
         let local = path::PathBuf::from_str(&self.path).unwrap();
 
diff --git a/tests/errors.rs b/tests/errors.rs
index 703dddd..9004cbe 100644
--- a/tests/errors.rs
+++ b/tests/errors.rs
@@ -1,11 +1,10 @@
-#![cfg(feature = "toml")]
+#![cfg(all(feature = "toml", feature = "preserve_order"))]
 
 extern crate config;
 
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use config::*;
@@ -97,7 +96,7 @@ fn test_error_enum_de() {
     ]
     .iter()
     .cloned()
-    .collect::<LinkedHashMap<String, Value>>()
+    .collect::<MapImpl<String, Value>>()
     .into();
     let confused_d = confused_v.try_into::<Diode>();
     assert_eq!(
diff --git a/tests/file_hjson.rs b/tests/file_hjson.rs
index 376993f..4439d31 100644
--- a/tests/file_hjson.rs
+++ b/tests/file_hjson.rs
@@ -7,7 +7,6 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use config::*;
@@ -21,7 +20,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
diff --git a/tests/file_json.rs b/tests/file_json.rs
index c3ebe06..035403c 100644
--- a/tests/file_json.rs
+++ b/tests/file_json.rs
@@ -7,7 +7,6 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use config::*;
@@ -21,7 +20,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -59,17 +58,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/file_json5.rs b/tests/file_json5.rs
index f92bce5..cb04718 100644
--- a/tests/file_json5.rs
+++ b/tests/file_json5.rs
@@ -9,7 +9,6 @@ extern crate serde_derive;
 
 use config::*;
 use float_cmp::ApproxEqUlps;
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 #[derive(Debug, Deserialize)]
@@ -20,7 +19,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -58,17 +57,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/file_ron.rs b/tests/file_ron.rs
index 71b9106..e1351b4 100644
--- a/tests/file_ron.rs
+++ b/tests/file_ron.rs
@@ -7,7 +7,6 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use config::*;
@@ -22,7 +21,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -61,17 +60,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/file_toml.rs b/tests/file_toml.rs
index 77d4d31..c0bcb31 100644
--- a/tests/file_toml.rs
+++ b/tests/file_toml.rs
@@ -7,7 +7,6 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use config::*;
@@ -22,7 +21,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -70,17 +69,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/file_yaml.rs b/tests/file_yaml.rs
index 4b1c108..18e34ad 100644
--- a/tests/file_yaml.rs
+++ b/tests/file_yaml.rs
@@ -7,7 +7,6 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use config::*;
@@ -21,7 +20,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -59,17 +58,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/get.rs b/tests/get.rs
index 43a126a..9cd6ecc 100644
--- a/tests/get.rs
+++ b/tests/get.rs
@@ -7,7 +7,6 @@ extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-use linked_hash_map::LinkedHashMap;
 use std::collections::HashSet;
 
 use config::*;
@@ -108,7 +107,7 @@ fn test_get_scalar_path_subscript() {
 #[test]
 fn test_map() {
     let c = make();
-    let m: LinkedHashMap<String, Value> = c.get("place").unwrap();
+    let m: MapImpl<String, Value> = c.get("place").unwrap();
 
     assert_eq!(m.len(), 8);
     assert_eq!(
@@ -121,23 +120,28 @@ fn test_map() {
 #[test]
 fn test_map_str() {
     let c = make();
-    let m: LinkedHashMap<String, String> = c.get("place.creator").unwrap();
-
-    assert_eq!(
-        m.into_iter().collect::<Vec<(String, String)>>(),
-        vec![
-            ("name".to_string(), "John Smith".to_string()),
-            ("username".to_string(), "jsmith".to_string()),
-            ("email".to_string(), "jsmith@localhost".to_string()),
-        ]
-    );
+    let m: MapImpl<String, String> = c.get("place.creator").unwrap();
+
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            m.into_iter().collect::<Vec<(String, String)>>(),
+            vec![
+                ("name".to_string(), "John Smith".to_string()),
+                ("username".to_string(), "jsmith".to_string()),
+                ("email".to_string(), "jsmith@localhost".to_string()),
+            ]
+        );
+    } else {
+        assert_eq!(m.len(), 3);
+        assert_eq!(m["name"], "John Smith".to_string());
+    }
 }
 
 #[test]
 fn test_map_struct() {
     #[derive(Debug, Deserialize)]
     struct Settings {
-        place: LinkedHashMap<String, Value>,
+        place: MapImpl<String, Value>,
     }
 
     let c = make();
@@ -222,7 +226,7 @@ fn test_enum() {
     }
     #[derive(Debug, Deserialize)]
     struct Settings {
-        diodes: LinkedHashMap<String, Diode>,
+        diodes: MapImpl<String, Diode>,
     }
 
     let c = make();
@@ -255,7 +259,7 @@ fn test_enum_key() {
 
     #[derive(Debug, Deserialize)]
     struct Settings {
-        proton: LinkedHashMap<Quark, usize>,
+        proton: MapImpl<Quark, usize>,
         // Just to make sure that set keys work too.
         quarks: HashSet<Quark>,
     }
@@ -271,7 +275,7 @@ fn test_enum_key() {
 fn test_int_key() {
     #[derive(Debug, Deserialize, PartialEq)]
     struct Settings {
-        divisors: LinkedHashMap<u32, u32>,
+        divisors: MapImpl<u32, u32>,
     }
 
     let c = make();
diff --git a/tests/legacy/errors.rs b/tests/legacy/errors.rs
index 070eb6d..4da586e 100644
--- a/tests/legacy/errors.rs
+++ b/tests/legacy/errors.rs
@@ -2,7 +2,6 @@
 
 extern crate config;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use self::config::*;
@@ -94,7 +93,7 @@ fn test_error_enum_de() {
     ]
     .iter()
     .cloned()
-    .collect::<LinkedHashMap<String, Value>>()
+    .collect::<MapImpl<String, Value>>()
     .into();
     let confused_d = confused_v.try_into::<Diode>();
     assert_eq!(
diff --git a/tests/legacy/file_hjson.rs b/tests/legacy/file_hjson.rs
index b846c91..8ca2d68 100644
--- a/tests/legacy/file_hjson.rs
+++ b/tests/legacy/file_hjson.rs
@@ -4,7 +4,6 @@ extern crate config;
 extern crate float_cmp;
 extern crate serde;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use self::config::*;
@@ -18,7 +17,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
diff --git a/tests/legacy/file_json.rs b/tests/legacy/file_json.rs
index 6a9b577..2486a55 100644
--- a/tests/legacy/file_json.rs
+++ b/tests/legacy/file_json.rs
@@ -4,7 +4,6 @@ extern crate config;
 extern crate float_cmp;
 extern crate serde;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use self::config::*;
@@ -18,7 +17,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -57,17 +56,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/legacy/file_ron.rs b/tests/legacy/file_ron.rs
index bfd31af..19b629d 100644
--- a/tests/legacy/file_ron.rs
+++ b/tests/legacy/file_ron.rs
@@ -4,7 +4,6 @@ extern crate config;
 extern crate float_cmp;
 extern crate serde;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use self::config::*;
@@ -19,7 +18,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -59,17 +58,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/legacy/file_toml.rs b/tests/legacy/file_toml.rs
index 24c590e..53310b4 100644
--- a/tests/legacy/file_toml.rs
+++ b/tests/legacy/file_toml.rs
@@ -4,7 +4,6 @@ extern crate config;
 extern crate float_cmp;
 extern crate serde;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use self::config::*;
@@ -19,7 +18,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -68,17 +67,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/legacy/file_yaml.rs b/tests/legacy/file_yaml.rs
index af04ef6..572e10c 100644
--- a/tests/legacy/file_yaml.rs
+++ b/tests/legacy/file_yaml.rs
@@ -4,7 +4,6 @@ extern crate config;
 extern crate float_cmp;
 extern crate serde;
 
-use linked_hash_map::LinkedHashMap;
 use std::path::PathBuf;
 
 use self::config::*;
@@ -18,7 +17,7 @@ struct Place {
     favorite: bool,
     telephone: Option<String>,
     reviews: u64,
-    creator: LinkedHashMap<String, Value>,
+    creator: MapImpl<String, Value>,
     rating: Option<f32>,
 }
 
@@ -57,17 +56,24 @@ fn test_file() {
     assert_eq!(s.place.telephone, None);
     assert_eq!(s.elements.len(), 10);
     assert_eq!(s.elements[3], "4".to_string());
-    assert_eq!(
-        s.place
-            .creator
-            .into_iter()
-            .collect::<Vec<(String, config::Value)>>(),
-        vec![
-            ("name".to_string(), "John Smith".into()),
-            ("username".into(), "jsmith".into()),
-            ("email".into(), "jsmith@localhost".into()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            s.place
+                .creator
+                .into_iter()
+                .collect::<Vec<(String, config::Value)>>(),
+            vec![
+                ("name".to_string(), "John Smith".into()),
+                ("username".into(), "jsmith".into()),
+                ("email".into(), "jsmith@localhost".into()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            s.place.creator["name"].clone().into_string().unwrap(),
+            "John Smith".to_string()
+        );
+    }
 }
 
 #[test]
diff --git a/tests/legacy/get.rs b/tests/legacy/get.rs
index c246567..6b12a57 100644
--- a/tests/legacy/get.rs
+++ b/tests/legacy/get.rs
@@ -4,7 +4,6 @@ extern crate config;
 extern crate float_cmp;
 extern crate serde;
 
-use linked_hash_map::LinkedHashMap;
 use std::collections::HashSet;
 
 use self::config::*;
@@ -106,7 +105,7 @@ fn test_get_scalar_path_subscript() {
 #[test]
 fn test_map() {
     let c = make();
-    let m: LinkedHashMap<String, Value> = c.get("place").unwrap();
+    let m: MapImpl<String, Value> = c.get("place").unwrap();
 
     assert_eq!(m.len(), 8);
     assert_eq!(
@@ -119,23 +118,28 @@ fn test_map() {
 #[test]
 fn test_map_str() {
     let c = make();
-    let m: LinkedHashMap<String, String> = c.get("place.creator").unwrap();
-
-    assert_eq!(
-        m.into_iter().collect::<Vec<(String, String)>>(),
-        vec![
-            ("name".to_string(), "John Smith".to_string()),
-            ("username".to_string(), "jsmith".to_string()),
-            ("email".to_string(), "jsmith@localhost".to_string()),
-        ]
-    );
+    let m: MapImpl<String, String> = c.get("place.creator").unwrap();
+
+    if cfg!(feature = "preserve_order") {
+        assert_eq!(
+            m.into_iter().collect::<Vec<(String, String)>>(),
+            vec![
+                ("name".to_string(), "John Smith".to_string()),
+                ("username".to_string(), "jsmith".to_string()),
+                ("email".to_string(), "jsmith@localhost".to_string()),
+            ]
+        );
+    } else {
+        assert_eq!(m.len(), 3);
+        assert_eq!(m["name"], "John Smith".to_string());
+    }
 }
 
 #[test]
 fn test_map_struct() {
     #[derive(Debug, Deserialize)]
     struct Settings {
-        place: LinkedHashMap<String, Value>,
+        place: MapImpl<String, Value>,
     }
 
     let c = make();
@@ -220,7 +224,7 @@ fn test_enum() {
     }
     #[derive(Debug, Deserialize)]
     struct Settings {
-        diodes: LinkedHashMap<String, Diode>,
+        diodes: MapImpl<String, Diode>,
     }
 
     let c = make();
@@ -253,7 +257,7 @@ fn test_enum_key() {
 
     #[derive(Debug, Deserialize)]
     struct Settings {
-        proton: LinkedHashMap<Quark, usize>,
+        proton: MapImpl<Quark, usize>,
         // Just to make sure that set keys work too.
         quarks: HashSet<Quark>,
     }
@@ -269,7 +273,7 @@ fn test_enum_key() {
 fn test_int_key() {
     #[derive(Debug, Deserialize, PartialEq)]
     struct Settings {
-        divisors: LinkedHashMap<u32, u32>,
+        divisors: MapImpl<u32, u32>,
     }
 
     let c = make();
diff --git a/tests/legacy/merge.rs b/tests/legacy/merge.rs
index 75cb16d..d93724d 100644
--- a/tests/legacy/merge.rs
+++ b/tests/legacy/merge.rs
@@ -3,7 +3,6 @@
 extern crate config;
 
 use self::config::*;
-use linked_hash_map::LinkedHashMap;
 
 fn make() -> Config {
     let mut c = Config::default();
@@ -24,15 +23,22 @@ fn test_merge() {
     assert_eq!(c.get("production").ok(), Some(true));
     assert_eq!(c.get("place.rating").ok(), Some(4.9));
 
-    let m: LinkedHashMap<String, String> = c.get("place.creator").unwrap();
-    assert_eq!(
-        m.into_iter().collect::<Vec<(String, String)>>(),
-        vec![
-            ("name".to_string(), "Somebody New".to_string()),
-            ("username".to_string(), "jsmith".to_string()),
-            ("email".to_string(), "jsmith@localhost".to_string()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        let m: MapImpl<String, String> = c.get("place.creator").unwrap();
+        assert_eq!(
+            m.into_iter().collect::<Vec<(String, String)>>(),
+            vec![
+                ("name".to_string(), "Somebody New".to_string()),
+                ("username".to_string(), "jsmith".to_string()),
+                ("email".to_string(), "jsmith@localhost".to_string()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            c.get("place.creator.name").ok(),
+            Some("Somebody New".to_string())
+        );
+    }
 }
 
 #[test]
diff --git a/tests/merge.rs b/tests/merge.rs
index 922ae31..93e2f39 100644
--- a/tests/merge.rs
+++ b/tests/merge.rs
@@ -3,7 +3,6 @@
 extern crate config;
 
 use config::*;
-use linked_hash_map::LinkedHashMap;
 
 fn make() -> Config {
     Config::builder()
@@ -21,15 +20,22 @@ fn test_merge() {
     assert_eq!(c.get("production").ok(), Some(true));
     assert_eq!(c.get("place.rating").ok(), Some(4.9));
 
-    let m: LinkedHashMap<String, String> = c.get("place.creator").unwrap();
-    assert_eq!(
-        m.into_iter().collect::<Vec<(String, String)>>(),
-        vec![
-            ("name".to_string(), "Somebody New".to_string()),
-            ("username".to_string(), "jsmith".to_string()),
-            ("email".to_string(), "jsmith@localhost".to_string()),
-        ]
-    );
+    if cfg!(feature = "preserve_order") {
+        let m: MapImpl<String, String> = c.get("place.creator").unwrap();
+        assert_eq!(
+            m.into_iter().collect::<Vec<(String, String)>>(),
+            vec![
+                ("name".to_string(), "Somebody New".to_string()),
+                ("username".to_string(), "jsmith".to_string()),
+                ("email".to_string(), "jsmith@localhost".to_string()),
+            ]
+        );
+    } else {
+        assert_eq!(
+            c.get("place.creator.name").ok(),
+            Some("Somebody New".to_string())
+        );
+    }
 }
 
 #[test]